This invention concerns a sealing device for chromium-plating tanks of bars and the like, of the type in which the bars or pieces to be chromium-plated, having a variable profile, are made to move continuously through an anode immersed in a chromium-plating bath contained in a tank whose furthermost ends are provided with suitable sealing devices, in correspondence with apertures for passage of the bars.
In continuously chromium-plating of bars or large elongated pieces whose sectional profile may at times be constant and at times present variable sections both in width and with regard to geometric conformation, such as for example, in the case of large connecting rods, large piston rods, trunnions for mobile plates of presses or the like, the problem of sealing in the chromium-plating fluid is difficult to solve. In fact, with pads of normal rubber or other types of seals, it is only possible to achieve a perfect seal in particular cases and for small-diameter cylindrical bars; whereas in the case of very large bars or pieces, as defined, the chromium liquid tight, in a continuously chromium-plating process, has never been adequately solved due to the different features that the seals must possess.
In the above-mentioned cases, in fact, it is necessary to have seals made from sufficiently soft material, that is to say, which adapts perfectly to the peripheral profile of the bars, but which is also sturdy enough to withstand the pressure of the fluid, adapting itself, at the same time, to the variations in the sections along the length of the bar. The sealing problems with seals made of soft plastic material are heightened by the temperature of the chromium-plating bath, usually in the range of 50.degree. C., which helps to make the seal itself even more precarious. The scope of this invention is to provide a sealing device for continuously chromium-plating tanks for bars and the like, which makes use of flexible seals, suitably shaped according to the geometric shape of the cross-sections and profile of the bar, in order to adequately solve the sealing problems for bars of considerable thickness; said seals being made with the required features of softness and elasticity, for the reasons stated above. A further scope of this invention is to provide a sealing device as defined which makes use of two or more seals, coupled together, having features which integrate each other, to further ensure the best sealing conditions.